A light emitting device has been proposed for combining a light emitting unit and a fluorescent substance for absorbing at least a part of a light emitted from the light emitting unit to emit a light having a different wavelength, and emitting a light having a white mixed color. In particular, the light emitting device to be utilized as a light source for illumination includes a plurality of light emitting units to increase the luminance, and furthermore, a phosphor to be excited by the light emitting units is provided in the vicinity of the light emitting unit. Consequently, the wavelength conversion efficiency of the phosphor can be enhanced. For example, a light emitting diode disclosed in Japanese Published Patent Document JP-A-2004-80046 has a red light emitting unit, a blue light emitting unit, and a phosphor to be excited by the blue light emitting unit to emit an emission spectrum for compensating for a light emitting intensity in a wavelength band between a blue wavelength band and a red wavelength band. The phosphor is filled in the cup of a lead frame having the blue light emitting unit and the red light emitting unit mounted thereon and covers the blue light emitting unit and the red light emitting unit. Moreover, one of the electrodes of each of the red light emitting unit and the blue light emitting unit is connected to each of different lead electrodes, and the red light emitting unit or the blue light emitting unit can also be caused to emit a light separately. By such a light emitting diode, consequently, it is possible to obtain a light emitting diode having a high color reproducibility and a high luminous efficiency.
In a light emitting device which can be utilized as an onboard light source, furthermore, a plurality of light emitting units is arranged in such a manner that an irradiated light has a predetermined light distribution pattern, and a light transforming member containing a phosphor is applied to the light emitting units. A predetermined one of the light emitting units is selected and driven so that the selected light emitting unit emits a light and a desirable light distribution pattern formed by a light having a mixed color of the emitted light and the fluorescence of the phosphor is observed.
In some cases in which the light emitting units are provided close to each other, however, light emitted from the driven light emitting unit excites a phosphor applied to another light emitting unit which is not driven. Consequently, light having a mixed color is observed from the region of another light emitting unit which is not driven (this phenomenon will be hereinafter referred to as “pseudo lighting” in this specification). When the pseudo lighting is generated, the contour of the light distribution pattern formed by the irradiation of a light from a light emitting device becomes unclear. In some cases, the size of the light source emitting the mixed color light is increased, which is disadvantageous to the optical design of a light source for a vehicle. The pseudo lighting is thus generated, so that a light emitting device having a desirable optical characteristic cannot be obtained.
Therefore, it would be desirable to provide a light emitting device having an excellent optical characteristic without causing the pseudo lighting.